A wireless ad hoc network (WANET) is a decentralized type of wireless network. The network is ad hoc because it does not rely on a pre-existing infrastructure, such as routers in wired networks or access points in managed (infrastructure) wireless networks. Instead, each node participates in routing by forwarding data for other nodes, so the determination of which nodes forward data is made dynamically on the basis of network connectivity. In addition to the classic routing, ad hoc networks can use flooding for forwarding data.
Based on WANET concept, Wi-Fi Alliance introduces Wi-Fi Neighbor Awareness Networking (NAN) technology, which allows Wi-Fi devices to continuously discover other interesting services and devices. The Wi-Fi NAN is built upon the interaction of NAN devices grouped in clusters. Clusters are automatically created by nearby NAN devices that cooperate to synchronize to a common schedule. During that schedule, all NAN devices participating in the cluster are allowed to exchange service frames describing or requesting a service.
In addition, a NAN device could join more than one cluster, and each cluster has different schedule for negotiation. However, different clusters could not directly communicate with each other, and thus power consumption or service interruption may occur. For example, a service subscriber is looking for a service provided by a service provider. The service subscriber cannot receive the service from the service provider since the service provider and the service subscriber are too far apart. Reference is made to FIG. 1, which illustrates data transmission and reception in different data link clusters. In FIG. 1, there are two NAN clusters NDC_O and NDC_B, wherein the NAN cluster NDC_O includes the NAN devices NAN_1-NAN_3 and the NAN cluster NDC_B includes the NAN devices NAN_3-NAN_5. The NAN clusters NDC_O and NDC_B have their own schedule, and thus the NAN devices NAN_1-NAN_5 of the NAN clusters NDC_O and NDC_B wake up for data transmission and reception at different time slots. In FIG. 1, the NAN device NAN_2 of the NAN cluster NDC_O is played as the service provider SP, and the NAN device NAN_5 of the NAN cluster NDC_B is played as the service subscriber SS. In this case, the NAN_5 may not get the service from the NAN device NAN_2 since the NAN device NAN_2 is far from the NAN device NAN_5.
In another example, reference is made to FIG. 2. The NAN_3 of the NAN clusters NDC_O and NDC_B is played as the SP, the NAN_2 of the NAN cluster NDC_O and the NAN_5 of NAN cluster NDC_B are played as the SS. In this case, the NAN_3 has to transmit the service frame twice for the clusters NDC_O and NDC_B since the NAN_2 and NAN_5 are in different clusters with different schedules. In other words, the NAN_3 transmits the same data for each cluster due to the NAN devices NAN_2 and NAN_5 of the clusters NDC_O and NDC_B wake up at different time slots, which cause power consumption in the NAN device NAN_3.